EP0350659B1 - Process for the separation of paraffinic and olefinic c4-hydrocarbons - Google Patents

Process for the separation of paraffinic and olefinic c4-hydrocarbons Download PDF

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EP0350659B1
EP0350659B1 EP89111093A EP89111093A EP0350659B1 EP 0350659 B1 EP0350659 B1 EP 0350659B1 EP 89111093 A EP89111093 A EP 89111093A EP 89111093 A EP89111093 A EP 89111093A EP 0350659 B1 EP0350659 B1 EP 0350659B1
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column
solvent
extractive distillation
paraffins
distillation column
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EP0350659A1 (en
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Gerd Emmrich
Hans-Christoph Schneider
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Krupp Koppers GmbH
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D3/00Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • B01D3/40Extractive distillation
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00Purification; Separation; Use of additives
    • C07C7/04Purification; Separation; Use of additives by distillation
    • C07C7/05Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
    • C07C7/08Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by extractive distillation

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  • the invention relates to a process for the separation of paraffinic and olefinic C4-hydrocarbons by extractive distillation using anhydrous morpholine as a selective solvent, the olefins being drawn off from the bottom of the extractive distillation column together with the majority of the solvent and being separated from the solvent in a downstream stripping column, while the paraffins are removed as top product from the extractive distillation column.
  • EP-B1-216 991 discloses a process of the type mentioned at the outset in which anhydrous morpholine is used as the selective solvent.
  • US Pat. No. 2,588,056 also describes a process for separating propene and propane by extractive distillation, in which acetonitrile or hydrocarbons from the group of acetonitriles or chloroacetonitriles are to be used as the selective solvent. It is proposed that the propane obtained as the top product of the extractive distillation be freed from solvent residues in a column located at the top of the extractive distillation column and referred to as a dephlegmator.
  • the invention was therefore based on the object of further optimizing the method of the type mentioned at the beginning and, in particular, of simplifying the processing of raffinate.
  • the process of the type mentioned at the outset serving to achieve this object is characterized according to the invention in that the solvent residues contained in the paraffins are removed from the paraffins in a column assembly which forms an integral unit with the extractive distillation column and is also provided with trays or other internals, the column top being removed with a reflux ratio of 1 to 2 is operated.
  • the paraffins are not treated in a separate column.
  • the extractive distillation column is provided with an additional column attachment above the solvent feed plate, which only needs to have a few plates, for example 10. This column attachment is sufficient at a reflux ratio of 1 to 2 to retain the solvent residues contained in the paraffins.
  • the anhydrous morpholine used as a solvent in carrying out the process according to the invention is distinguished on the one hand for the stated purpose by particularly good selectivity and good solvent properties, so that high olefin yields of the order of> 99% can be achieved even at low olefin concentrations in the feed product.
  • the solvent is used without any addition of water, subsequent dehydration (drying) of both the raffinate and the extract can be dispensed with, so that both products can be readily reacted in water-sensitive reactions.
  • Caff fractions containing paraffins and olefins as they come into question incurred in various technical processes.
  • Typical examples are the mixtures already mentioned at the beginning, which occur after the removal of the butadiene and the isobutene from C aus fractions in the production of ethylene or the catalytic or thermal cracking of hydrocarbons.
  • such mixtures contain in particular iso- and n-butane, butene-1 and cis / trans-butene-2.
  • the apparatuses and systems customary and generally used for extractive distillation can be used to carry out this process.
  • the process of the method of operation according to the invention is shown in a simplified form in the flow diagram shown in the figure.
  • the feed product to be separated is introduced through the line 1 in the liquid state into the middle part of the extractive distillation column 2 provided with trays or other internals.
  • the column attachment 4 Above the mouth of the line 3 into the extractive distillation column 2, that is above the solvent feed tray, the column attachment 4 is arranged, which forms a structural unit with the extractive distillation column 2 and which is also provided with trays or other internals.
  • the paraffin vapors rising from the extractive distillation column 2 therefore get directly into the column attachment 4.
  • the solvent residues still present in the paraffins are washed out by the reflux fed via line 16, so that the paraffins in the pure state are withdrawn via the head 15 and theirs can be used for further use.
  • Line 16 branches off from line 15 for the required reflux.
  • the liquid bottom product of the extractive distillation column 2 consists of the solvent and the olefins dissolved therein.
  • the extractive distillation column 2 It is drawn off from the extractive distillation column 2 through line 5 and reaches the stripping column 6, in which the olefins are separated from the solvent by distillation.
  • the solvent is removed from the bottom of the column through line 7 and, after appropriate cooling, which is generally achieved in an economical heat network within the system, returns via line 3 to the extractive distillation column 2, while the olefin vapors pass overhead from the stripping column 6 escape and through the Line 8 are fed to their further processing.
  • the branch line 9 is provided in the area of the line 7, through which a partial amount of the solvent can reach the regeneration device 11 when the valve 10 is in the appropriate position.
  • the regenerated solvent is returned to the circuit (line 7) through line 12, while the separated impurities are drawn off from the regeneration device 11 through line 13.
  • the line 14 is finally used to supply fresh solvent.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
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  • Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Trennung von paraffinischen und olefinischen C₄-Kohlenwasserstoffen durch Extraktivdestillation unter Verwendung von wasserfreiem Morpholin als selektives Lösungsmittel, wobei die Olefine zusammen mit der Hauptmenge des Lösungsmittels aus dem Sumpf der Extraktivdestillationskolonne abgezogen und in einer nachgeschalteten Abtriebskolonne vom Lösungsmittel abgetrennt werden, während die Paraffine als Kopfprodukt aus der Extraktivdestillationskolonne entfernt werden.The invention relates to a process for the separation of paraffinic and olefinic C₄-hydrocarbons by extractive distillation using anhydrous morpholine as a selective solvent, the olefins being drawn off from the bottom of the extractive distillation column together with the majority of the solvent and being separated from the solvent in a downstream stripping column, while the paraffins are removed as top product from the extractive distillation column.

Aus den auf der Basis von Naphtha als Einsatzprodukt arbeitenden Äthylen-Steamcrackern sowie in katalytischen Crackanlagen fallen in der chemischen Industrie große Mengen an C₄-Fraktionen an, die neben stärker ungesättigten C₄-Kohlenwasserstoffen insbesondere C₄-Paraffine und C₄-Monoolefine enthalten. Auf Grund ihrer hohen Reaktionsfähigkeit werden dabei die C₄-Monoolefine im zunehmenden Maße als Ausgangsstoffe für weiterführende Reaktionen eingesetzt. Aus diesem Grunde ist das Interesse der Fachwelt an einer wirtschaftlichen Auftrennung der anfallenden C₄-Fraktionen ständig gewachsen. Es sind deshalb bereits Verfahrensgänge entwickelt worden, bei denen zunächst aus der eingesetzten C₄-Fraktion das Butadien durch Gaswäsche oder Extraktivdestillation mit speziellen Lösungsmitteln abgetrennt wird, während das Isobuten durch Selektivreaktionen wie Schwefelsäureesterbildung oder die Herstellung von Methyl-tert.-Butylether (MTB) aus dem Einsatzprodukt entfernt wird. Die danach im Einsatzprodukt verbleibenden Komponenten Isobutan, n-Butan, Buten-1 und cis/trans-Buten 2 sind auf Grund ihrer Siedelage nur noch schwer, zum Teil aber auch gar nicht auf rein destillativem Wege zu trennen. Es besteht deshalb derzeit bei der Fachwelt ein ausgesprochenes Bedürfnis nach Verfahren, die die Trennung der genannten Verbindungen auf einfache und besonders wirtschaftliche Weise ermöglichen.From the ethylene steam crackers based on naphtha as an input product and in catalytic cracking plants, large amounts of C₄ fractions are obtained in the chemical industry, which in addition to more unsaturated C₄ hydrocarbons contain in particular C₄ paraffins and C₄ monoolefins. Due to their high reactivity, the C₄ monoolefins are increasingly used as starting materials for further reactions. For this reason, the interest of the professional world in an economic separation of the resulting C₄ fractions has grown steadily. Processes have therefore already been developed in which the butadiene is first separated from the C₄ fraction used by gas scrubbing or extractive distillation with special solvents, while the isobutene is isolated by selective reactions such as sulfuric acid ester formation or the production of methyl tert-butyl ether (MTB) the input product is removed. The components isobutane, n-butane, butene-1 remaining in the feed product thereafter and cis / trans-butene 2 are difficult to separate due to their settling position, but sometimes not at all by purely distillative means. Therefore, there is currently a pronounced need among experts for processes which enable the separation of the compounds mentioned in a simple and particularly economical manner.

In diesem Zusammenhang ist bereits vorgeschlagen worden, die Trennung von paraffinischen und olefinischen C₄-Kohlenwasserstoffen durch Extraktivdestillation unter Verwendung eines selektiven Lösungsmittels vorzunehmen. So ist beispielsweise aus der EP-B1-216 991 ein Verfahren der eingangs genannten Art bekannt, bei dem als selektives Lösungsmittel wasserfreies Morpholin zur Anwendung gelangt.In this context, it has already been proposed to carry out the separation of paraffinic and olefinic C₄-hydrocarbons by extractive distillation using a selective solvent. For example, EP-B1-216 991 discloses a process of the type mentioned at the outset in which anhydrous morpholine is used as the selective solvent.

In der US-A-2 588 056 wird ferner ein Verfahren zur Trennung von Propen und Propan durch Extraktivdestillation beschrieben, bei dem Acetonitril oder Kohlenwasserstoffe aus der Gruppe der Acetonitrile oder Chloracetonitrile als selektives Lösungsmittel verwendet werden sollen. Dabei wird vorgeschlagen, das als Kopfprodukt der Extraktivdestillation anfallende Propan in einer am Kopf der Extraktivdestillationskolonne angeordneten und als Dephlegmator bezeichneten Kolonne von Lösungsmittelresten zu befreien.US Pat. No. 2,588,056 also describes a process for separating propene and propane by extractive distillation, in which acetonitrile or hydrocarbons from the group of acetonitriles or chloroacetonitriles are to be used as the selective solvent. It is proposed that the propane obtained as the top product of the extractive distillation be freed from solvent residues in a column located at the top of the extractive distillation column and referred to as a dephlegmator.

Das heißt, bei der Durchführung derartiger Extraktivdestillationen war es bisher üblich, daß die Paraffine, die als Raffinat über Kopf aus der Extraktivdestillationskolonne abgezogen werden, in einer separaten Kolonne durch Destillation von den in ihnen noch enthaltenen Lösungsmittelresten abgetrennt werden. Es liegt auf der Hand, daß eine derartige Kolonne zur Raffinataufarbeitung zusätzliche Betriebs- und Anlagekosten verursacht.That is, when carrying out such extractive distillations, it was previously customary for the paraffins which are withdrawn as raffinate overhead from the extractive distillation column to be separated from the solvent residues still contained in them in a separate column by distillation. It is obvious that such a column for raffinate processing causes additional operating and plant costs.

Der Erfindung lag deshalb die Aufgabe zugrunde, das Verfahren der eingangs genannten Art weiter zu optimieren und insbesondere die Raffinataufarbeitung zu vereinfachen.The invention was therefore based on the object of further optimizing the method of the type mentioned at the beginning and, in particular, of simplifying the processing of raffinate.

Das der Lösung dieser Aufgabe dienende Verfahren der eingangs genannten Art ist erfindungsgemäß dadurch gekennzeichnet, daß die in den Paraffinen enthaltenen Lösungsmittelreste in einem mit der Extraktivdestillationskolonne einebauliche Einheit bildenden und ebenfalls mit Böden oder sonstigen Einbauten versehenen Kolonnenaufsatz aus den Paraffinen entfernt werden, wobei der Kolonnenaufsatz mit einem Rückflußverhältnis von 1 bis 2 betrieben wird.The process of the type mentioned at the outset serving to achieve this object is characterized according to the invention in that the solvent residues contained in the paraffins are removed from the paraffins in a column assembly which forms an integral unit with the extractive distillation column and is also provided with trays or other internals, the column top being removed with a reflux ratio of 1 to 2 is operated.

Das heißt, beim erfindungsgemäßen Verfahren wird auf eine Behandlung der Paraffine in einer separaten Kolonne verzichtet. Stattdessen wird die Extraktivdestillationskolonne oberhalb des Lösungsmittelaufgabebodens mit einem zusätzlichen Kolonnenaufsatz versehen, der nur wenige Böden, beispielsweise 10, aufzuweisen braucht. Dieser Kolonnenaufsatz reicht bei einem Rückflußverhältnis von 1 bis 2 aus, um die in den Paraffinen enthaltenen Lösungsmittelreste zurückzuhalten.This means that in the process according to the invention, the paraffins are not treated in a separate column. Instead, the extractive distillation column is provided with an additional column attachment above the solvent feed plate, which only needs to have a few plates, for example 10. This column attachment is sufficient at a reflux ratio of 1 to 2 to retain the solvent residues contained in the paraffins.

Dieses Ergebnis, das im Hinblick auf die bisher geübte Praxis als überraschend angesehen werden muß, läßt sich im wesentlichen mit der besonderen Zusammensetzung der in diesem Falle als Einsatzprodukt zur Anwendung gelangenden C₄-Fraktionen erklären. Diese C₄-Fraktionen enthalten nur paraffinische und olefinische C₄-Kohlenwasserstoffe, wobei das n-Butan die schwerste Komponente darstellt. Im Gegensatz zur Aufarbeitung anderer Kohlenwasserstoffgemische durch Extraktivdestillation, wie z.B. der Aromatengewinnung, fehlt hier im Einsatzprodukt eine kritische Schlüsselkomponente, wie z.B. Methylcyclohexan, die sich durch Rückfluß im Oberteil der Extraktivdestillationskolonne aufkonzentrieren und dann entweder in den Kolonnensumpf durchschlagen und dort die Reinheit des Extraktives verschlechtern oder sich in dem Maße unterhalb der Lösungsmittelaufgabe anreichern würde, daß dadurch eine Entmischung von Lösungsmittel- und Raffinaphase auftritt. Im Gegensatz dazu läßt sich das n-Butan jedoch zusammen mit dem iso-Butan problemlos über Kopf aus der Extraktivdestillationskolonne abdestillieren und zeigt deshalb die vorstehend beschriebenen Erscheinungen nicht.This result, which must be regarded as surprising in view of the practice practiced hitherto, can essentially be explained by the special composition of the C₄ fractions used in this case as a feed product. These C₄ fractions contain only paraffinic and olefinic C₄ hydrocarbons, with the n-butane being the heaviest component. In contrast to the processing of other hydrocarbon mixtures by extractive distillation, such as the extraction of aromatics, a critical key component, such as methylcyclohexane, is missing in the feed product, which is caused by reflux in the upper part Concentrate the extractive distillation column and then either penetrate into the bottom of the column and deteriorate the purity of the extractive there or would accumulate to the extent below the solvent charge that separation of the solvent and raffinate phases would occur. In contrast, however, the n-butane can be distilled off together with the isobutane from the extractive distillation column without problems and therefore does not show the phenomena described above.

Es liegt auf der Hand, daß durch die erfindungsgemäße Verwendung eines Kolonnenaufsatzes auf der Extraktivdestillationsklonne anstelle einer separaten Kolonne die Betriebs- und Anlagekosten für die Raffinatbehandlung nicht unbeträchtlich verringert werden und der Verfahrensablauf insgesamt vereinfacht wird.It is obvious that the use of a column attachment according to the invention on the extractive distillation column instead of a separate column does not inconsiderably reduce the operating and plant costs for the raffinate treatment and the process sequence as a whole is simplified.

Das bei der Durchführung des erfindungsgemäßen Verfahrens als Lösungsmittel verwendete wasserfreie Morpholin zeichnet sich einerseits für den genannten Zweck durch besonders gute Selektivität und gute Lösungsmitteleigenschaften aus, so daß auch bei niedrigen Olefinkonzentrationen im Einsatzprodukt hohe Olefinausbeuten in der Größenordnung von > 99 % erreicht werden können. Andererseits kann, da das Lösungsmittel ohne jeden Wasserzusatz angewandt wird, auf eine nachträgliche Entwässerung (Trocknung) sowohl des Raffinates als auch des Extraktes verzichtet werden, so daß beide Produkte ohne weiteres in wasserempfindlichen Reaktionen weiter umgesetzt werden können.The anhydrous morpholine used as a solvent in carrying out the process according to the invention is distinguished on the one hand for the stated purpose by particularly good selectivity and good solvent properties, so that high olefin yields of the order of> 99% can be achieved even at low olefin concentrations in the feed product. On the other hand, since the solvent is used without any addition of water, subsequent dehydration (drying) of both the raffinate and the extract can be dispensed with, so that both products can be readily reacted in water-sensitive reactions.

Als Einsatzprodukt für das erfindungsgemäße Verfahren kommen, wie bereits weiter oben gesagt wurde, Paraffine und Olefine enthaltende C₄-Fraktionen in Frage, wie sie bei verschiedenen technischen Prozessen anfallen. Typische Beispiele sind die bereits eingangs erwähnten Gemische, die nach der Entfernung des Butadiens sowie des Isobutens aus C₄-Fraktionen der Äthylen-Erzeugung oder der katalytischen bzw. thermischen Crackung von Kohlenwasserstoffen anfallen. Derartige Gemische enthalten, wie bereits erwähnt wurde, insbesondere Iso- und n-Butan, Buten-1 sowie cis/trans-Buten-2. Es gibt daneben aber auch technische Aufarbeitungswege, bei denen Gemische anfallen, in denen neben iso- und n-Butan nur cis/trans-Buten-2 oder nur n-Butan und cis/trans-Buten-2 enthalten sind. Die gemeinsame Gewinnung von Buten-1 und cis/trans-Buten-2 aus diesen Gemischen ist vor allem in den Fällen von Interesse, bei denen die drei Olefine als gleichrangige Reaktionspartner reagieren, was z.B. bei der weiteren Umsetzung zu Methyläthylketon der Fall ist. Auch die Isolierung von cis/trans-Buten-2 aus Gemischen mit n-Butan ist von besonderem Interesse, beispielsweise für die Oligomerisierung zu vorzugsweise Octen. Für alle diese Trennungen ist das erfindungsgemäße Verfahren besonders gut geeignet.As a starting product for the process according to the invention, as already mentioned above, Caff fractions containing paraffins and olefins, as they come into question incurred in various technical processes. Typical examples are the mixtures already mentioned at the beginning, which occur after the removal of the butadiene and the isobutene from C aus fractions in the production of ethylene or the catalytic or thermal cracking of hydrocarbons. As already mentioned, such mixtures contain in particular iso- and n-butane, butene-1 and cis / trans-butene-2. However, there are also technical processing routes in which mixtures are obtained which, in addition to iso- and n-butane, contain only cis / trans-butene-2 or only n-butane and cis / trans-butene-2. The common production of butene-1 and cis / trans-butene-2 from these mixtures is of particular interest in those cases in which the three olefins react as reaction partners of equal rank, which is the case, for example, in the further conversion to methyl ethyl ketone. The isolation of cis / trans-butene-2 from mixtures with n-butane is also of particular interest, for example for the oligomerization to preferably octene. The method according to the invention is particularly well suited for all of these separations.

Für die Durchführung dieses Verfahrens können die für Extraktivdestillationen üblichen und allgemein gebräuchlichen Apparaturen und Anlagen eingesetzt werden. Der Verfahrensgang der erfindungsgemäßen Arbeitsweise ist dabei in dem in der Abbildung dargestellten Fließschema in vereinfachter Form wiedergegeben. Das aufzutrennende Einsatzprodukt wird hierbei durch die Leitung 1 im flüssigen Zustand in den mittleren Teil der mit Böden oder sonstigen Einbauten versehenen Extraktivdestillationskolonne 2 eingeleitet. Durch die Leitung 3 wird das Lösungsmittel in die Extraktivdestillationskolonne 2 eingeleitet und fließt über die Einbauten dieser Kolonne herab nach unten, wobei es die Olefine aufnimmt.The apparatuses and systems customary and generally used for extractive distillation can be used to carry out this process. The process of the method of operation according to the invention is shown in a simplified form in the flow diagram shown in the figure. The feed product to be separated is introduced through the line 1 in the liquid state into the middle part of the extractive distillation column 2 provided with trays or other internals. Through line 3 that Solvent introduced into the extractive distillation column 2 and flows down over the internals of this column, whereby it takes up the olefins.

Oberhalb der Einmündung der Leitung 3 in die Extraktivdestillationskolonne 2, das heißt oberhalb des Lösungsmittelaufgabebodens, ist der Kolonnenaufsatz 4 angeordnet, der mit der Extraktivdestillationskolonne 2 eine bauliche Einheit bildet, und der ebenfalls mit Böden oder sonstigen Einbauten versehen ist. Die aus der Extraktivdestillationskolonne 2 aufsteigenden Paraffindämpfe gelangen deshalb unmittelbar in den Kolonnenaufsatz 4. Hier werden durch den über die Leitung 16 aufgegebenen Rückfluß die in den Paraffinen noch vorhandenen Lösungsmittelreste ausgewaschen, so daß die Paraffine im reinen Zustand über die Leitung 15 über Kopf abgezogen und ihrer weiteren Verwendung zugeführt werden können. Von der Leitung 15 zweigt dabei die Leitung 16 für den erforderlichen Rückfluß ab. Das flüssige Sumpfprodukt der Extraktivdestillationskolonne 2 besteht aus dem Lösungsmittel und den darin gelösten Olefinen. Es wird durch die Leitung 5 aus der Extraktivdestillationskolonne 2 abgezogen und gelangt in die Abtriebskolonne 6, in der die Olefine destillativ vom Lösungsmittel abgetrennt werden. Das Lösungsmittel wird durch die Leitung 7 aus dem Kolonnensumpf entfernt und gelangt nach entsprechender Abkühlung, die im allgemeinen in einem wirtschaftlichen Wärmeverbund innerhalb der Anlage erreicht wird, über die Leitung 3 wieder in die Extraktivdestillationskolonne 2 zurück, während die Olefindämpfe über Kopf aus der Abtriebskolonne 6 entweichen und durch die Leitung 8 ihrer weiteren Verarbeitung zugeführt werden. Da sich im Laufe der Zeit im Lösungsmittel Verunreinigungen anreichern können, ist im Bereich der Leitung 7 die Abzweigleitung 9 vorgesehen, durch die bei entsprechender Stellung des Ventils 1o eine Teilmenge des Lösungsmittels zur Regeneriereinrichtung 11 gelangen kann. Das regenerierte Lösungsmittel wird durch die Leitung 12 wieder in den Kreislauf (Leitung 7) zurückgeführt, während die ausgeschiedenen Verunreinigungen durch die Leitung 13 aus der Regeneriereinrichtung 11 abgezogen werden. Die Leitung 14 dient schließlich der Zufuhr von frischem Lösungsmittel.Above the mouth of the line 3 into the extractive distillation column 2, that is above the solvent feed tray, the column attachment 4 is arranged, which forms a structural unit with the extractive distillation column 2 and which is also provided with trays or other internals. The paraffin vapors rising from the extractive distillation column 2 therefore get directly into the column attachment 4. Here, the solvent residues still present in the paraffins are washed out by the reflux fed via line 16, so that the paraffins in the pure state are withdrawn via the head 15 and theirs can be used for further use. Line 16 branches off from line 15 for the required reflux. The liquid bottom product of the extractive distillation column 2 consists of the solvent and the olefins dissolved therein. It is drawn off from the extractive distillation column 2 through line 5 and reaches the stripping column 6, in which the olefins are separated from the solvent by distillation. The solvent is removed from the bottom of the column through line 7 and, after appropriate cooling, which is generally achieved in an economical heat network within the system, returns via line 3 to the extractive distillation column 2, while the olefin vapors pass overhead from the stripping column 6 escape and through the Line 8 are fed to their further processing. Since impurities can accumulate in the solvent over time, the branch line 9 is provided in the area of the line 7, through which a partial amount of the solvent can reach the regeneration device 11 when the valve 10 is in the appropriate position. The regenerated solvent is returned to the circuit (line 7) through line 12, while the separated impurities are drawn off from the regeneration device 11 through line 13. The line 14 is finally used to supply fresh solvent.

Durch Anwendung des erfindungsgemäßen Verfahrens ist es bei gleich guten Trennergebnissen möglich, eine Einsparung an Betriebs- und Anlagekosten in der Größenordnung von 1o - 15 % gegenüber der bisher bekannten Arbeitsweise zu erzielen, bei der die Raffinatbehandlung in einer separaten Kolonne erfolgt.By using the method according to the invention it is possible, with equally good separation results, to achieve savings in operating and plant costs in the order of magnitude of 10-15% compared to the previously known method of working, in which the raffinate treatment takes place in a separate column.

Claims (1)

  1. A process for the separation of paraffinic and olefinic C₄ hydrocarbons by extractive distillation using anhydrous morpholine as a selective solvent, the olefins being drawn off from the bottom of the extractive distillation column (2), together with the bulk of the solvent, and separated from the solvent in a downstream stripper column (6), while the paraffins are removed from the extractive distillation column as the top product (15), characterised in that the solvent residues contained in the paraffins are removed from the paraffins in a column attachment (4) forming a structural unit with the extractive distillation column (2) and also provided with trays or other built-in parts, the column attachment being operated with a reflux ratio of 1 to 2.
EP89111093A 1988-07-14 1989-06-19 Process for the separation of paraffinic and olefinic c4-hydrocarbons Expired - Lifetime EP0350659B1 (en)

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DE3823772A DE3823772A1 (en) 1988-07-14 1988-07-14 METHOD FOR SEPARATING PARAFFINIC AND OLEFINIC C (ARROW DOWN) 4 (ARROW DOWN) HYDROCARBONS
DE3823772 1988-07-14

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EP0350659A1 EP0350659A1 (en) 1990-01-17
EP0350659B1 true EP0350659B1 (en) 1992-09-23

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FR2771418B1 (en) * 1997-11-25 2001-02-02 Inst Francais Du Petrole PROCESS FOR SEPARATING A C5-C8 LOAD OR AN INTERMEDIATE LOAD, INTO THREE EFFLUENTS RESPECTIVELY RICH IN LINEAR, SINGLE-BRANCHED AND MULTI-BRANCHED PARAFFINS
DE102005023549A1 (en) * 2005-05-21 2006-11-23 Oxeno Olefinchemie Gmbh Transition metal-catalyzed butene oligomerization uses a butene-rich stream obtained by extractive distillation, distillative separation, washing and drying from a stream containing saturated and unsaturated 4C hydrocarbons

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US2588056A (en) * 1947-09-30 1952-03-04 Sinclair Refining Co Separation of propene and propane by extractive distillation
BE789816A (en) * 1971-10-07 1973-02-01 Basf Ag PROCESS FOR OBTAINING CONJUGATED DIOLEFINS FROM MIXTURES OF C4 OR C5 HYDROCARBONS
JPS58167683A (en) * 1982-03-29 1983-10-03 Nippon Zeon Co Ltd Extractive distillation
DE3346695A1 (en) * 1983-12-23 1985-07-04 Basf Ag, 6700 Ludwigshafen METHOD FOR SEPARATING A C (DOWN ARROW) 4 (DOWN ARROW) HYDROCARBON MIXTURE BY EXTRACTIVE DISTILLATION
DE3532289A1 (en) * 1985-09-11 1987-03-19 Krupp Koppers Gmbh METHOD FOR SEPARATING PARAFFINIC AND OLEFINIC C (ARROW DOWN) 4 (ARROW DOWN) HYDROCARBONS

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